Spring balance with vertical linearizing means

ABSTRACT

A measuring instrument of the spring balance type for measuring a mass, through a measurement of force, which includes mounting means for a resilient member counteracting the force that maintains the axis of operation of the resilient member linear along the vertical.

United States Patent Lohmann [4 1 Oct. 17, 1972 [54] SPRING BALANCE WITHVERTICAL 3,647,010 3/1972 Beardmore ..l77/l70 72 Z I J E D b C FOREIGNPATENTS OR APPLICATIONS t I t l 1 men or o mg many 82,134 12/1920Austria ..*..177/230 Assigneer Berke! GmbH, Duisburg, Germa y 90,4812/1897 Germany", ..'177/234 151,061 5/1904 Germany ..l77/234 May 1971 7197,260 4/1908 Germany ..177/230 I21] Appl. No.: 145,324 72,108 4/1953Netherlands..... ..l77/23O v Prima Examiner-Robert SIWard, Jr. {30]Foreign Application Priority Data g, L Zicken May 29, 1970 Germany ..P20 26 309.6 [57] ABSTRACT [52] US. Cl. ..l77/230, 177/234, 177/168, A[measuring instrument f the Spring balance type for 177/246 measuring amass, through a measurement of force, lllt- Cl g 1/18, 8 g 21/00 whichincludes mounting means for a resilient member Field of Searchcounteracting the force that maintains the axis of 177/246 operation ofthe resilient member linear along the vertical. [56] References CitedUNITED STATES PATENTS 12 Claims, 1 Drawing Figure 1,946,775 2/1934Zwickl .1 77/16s [Hu 111M111 f 1 I 8 6 [[6 1mg lllllll' PATENTEDum 11I922 This invention relates in general to an instrument for measuring amass through the measurement of a force, such as in a weighing scale ora dynamometer, and more particularly to an instrument having anadjustable mounting for a resilient member counteracting the force.

. It is known to measure forces by measuring the variation in length ofan elastic member, e.g., a coiled spring, subjected to the action of theforce. This method is preferably employed in the case of springbalances, which are for this purpose calibrated in units of mass, usingstandard weights, at the place where the balance is erected, and thuspermit of obtaining a measurement of mass through a measurement offorce. The difficulty in constructing a spring balance lies in workingout an absolutely vertical linear path of movement for the spring whenit is expanding and contracting, in addition to which it is essential toobtain, by choosing the most suitable spring material, a minimum ofhysteresis and a low temperature dependency of the measuring range. i

The invention provides a means of overcoming this difficulty. Themeasuring instrument of the invention includes a spring balance with aspring serving as a force equalizer, especially a coiled spring with anadjusting device, wherein the ends of the spring are kept clamped inposition and their supports can be moved and set transversely to thelongitudinal axis of the spring. In this way his possible to obtain anadjustment which is brought about not only by varying the effectivelength of the spring or its number of turns, but by shifting thesupports of the spring-ends. Because of the rigid fixing of thesesupports, no variations can be introduced into the measuring system.Should any torsional effect of the spring still occur, it can becountered by incorporating an oppositely acting torsion springsuspension between the end of the spring and its suspension mounting,e.g., in the form of a steel band clamped in position at both ends.

Suspension of the ends of the spring in accordance with the invention isobtainable in that the end of the spring which is fixed in position whenthe spring is under load is supported on a bar which can be shiftedlaterally in stationary supports, wherein the end of the spring thatfollows the variation of its length when under load, is supported insuch a manner that it can be shifted laterally and pivoted. The movableend of the spring is connected to the main lever of the spring balancethrough an adjusting member that can be shifted in position along themain lever for initial adjustment and pivoted about a swivel pin forfine adjustment. Shifting of the adjusting member along the main leveris accomplished by providing a row of holes in the main lever and a rowof holes in the adjusting lever and a transferrable swivel pin forengaging an aligned set of holes, one of the main lever and one of theadjusting member. The holes in the adjusting member are spaced apart agreater or lesser distance than holes in the main lever to facilitateadjustment. Fine adjustment is accomplished by a pair of regulatingscrews or bolts acting on a tongue mounted to the adjusting member torotate the adjusting member about the swivel pin. expandible vide asupport fora balancing spring'in a measuring instrument permitting thespring to be adjusted while Accordingly, it is an object of thisinvention to promaintaining it expandible and contractible linearlyalong a vertical path.

Other objects, features and advantages of the invention will be apparentfrom the following detailed disclosure, taken in conjunction with theaccompanying sheet of drawing, wherein like reference numerals refer tolike parts, in which: 1

The single FIGURE illustrates a somewhat diagrammatic representation ofa typical embodiment of the invention in the form of a spring balancehaving a main leverl supported by a stationary knife bearing 2, andincluding lever arms la and 1b. The lever arm la carries a flexiblecounterpoise 3, wherein the lever arm lb is connected at its free endwith a set of rods which transmit its movement to theindicator device ofthe balance. The set of rods consists of a T-shaped arm 4 whose verticalshank 4a is pivotally connected at its end 5 with lever l and at itsother end 6 with the free end of a guide rod 8 which is pivotallymounted in stationary bearings at 7. The horizontal shank 9 of the arm 4carries at its free end 10 a toothed rack 11 engaging with a pinion 12which carries a weight indicator l3 coacting with a graduated scale 14.The load-scale carrier 16 of the balance is connected through a knifebearing 15, to the main lever l, at a point intermediate the endsthereof.

A bell-crank lever 17 having a long arm 18a and a short arm 18bfunctions to adjust the balance. The bell crank lever 17 is adjustablymounted on the main lever l and movable longitudinally and rotationallythereof. The adjusting lever 17 is supported on the main lever l in thecentral portion of a U-shaped bend 18 by a transferable swivel pin 20passing through holes formed in the main lever and the short arm 18b,which swivel pin 20 engages one hole in a row of holes 21 in the mainlever l aligned with one hole in a row of holes 22 in the 1 adjustinglever 17 The spacing of the holes is the same in each row but differentfrom that of the other row, so that a finer longitudinal adjustment canbe obtained when two holes are aligned in order to receive the swivelpin 20. The spacing of holes 22 is one and a half times that of the rowof holes 21, although it could be any desired ratio. At the free end ofthe longer arm 18a of the adjusting lever a tongue 23 is provided whichis engaged on opposite sides by two regulating screws 24, 25 carried'bythe main lever and positioned over each other which can be screwed intomountings adjacent a window-like cut-out 26 of the main lever l andfunction for fine adjustment of the balance. Movement of the regulatingscrews applies a force to the tongue 23 and causes rotation of theadjusting lever 17 about the swivel pin 20.

Retention of the position of adjustment is obtained by means ofaclamping bolt 27 that is received by the adjusting lever 17, whichcoacts with a disk 28 to overlap an elongated hole 29 in the main leverl. The hole 29 is of sufficient width with respect to the bolt to avoidobstructing the adjustment movements. Tightening of the bolt 27 clampsand locks the adjusting lever to the main lever against relativemovement.

The downward-pulling load therebetween on the load scale carrier 16transmits a pulling force through the main lever l and the adjustinglever 17 to a cylindrical coiled spring 30 whose ends are firmly clampedin position. The top end 31 of the spring is held by a screw 32 on atransverse bar support 33 which extends normal to the longitudinal axisof the spring and is adjustably clamped in stationary supports 34, 35 byset screws 36, 37, wherein the spring end 31 may be adjustablypositioned between the supports. The bottom end 38 of spring 30 isfirmly clamped in a clamping member 39 by a set screw 40.

A steel band 41 is supported at one of its ends to the clamping member39 by means of a clamping disk 42 and a bolt 43. The other end of thesteel band is clamped in a similar manner, by'means of a disk 44 and abolt 45, to a clamping member 46 of a bracket 47 carrying a bearing 48of a knife-blade bearing having a knife 49 carried at the junction ofthe arms of the adjusting lever 17. The steel band 31 counteractstorsional movement of the spring.

A first adjustment of the measuring instrument to change thelongitudinal axis of the spring is effected by loosening the clampingbolt 27 and set screws36, 37 and removing the swivel pin 20 so that theadjusting lever 17 may be shifted on the main lever 1, and the bar 33which supports the upper end 31 of spring 30 may be shifted along thesupports 34, 35. The position of adjustment is first set by insertingthe swivel pin 20 in aligned holes of the two rows of holes 21, 22 andtightening the set screws 36, 37. Thereafter, a fine adjustment may beeffected by actuating the two adjusting screws 24, 25, to rotate theadjusting lever 17 around the swivel pin 20, wherein the spacing betweenthe knife-blade bearing 48, 49 of the power arm on the adjusting lever17 and the knife bearing 15 of the loadarm on the main lever 1 can befurther changed, while maintaining the same effective spring-length,maintaining the same position of the knife bearings 2 and 15 of theload-arm together with the knife bearings 48, 49 of the power arm on astraight line, and maintaining along the vertical the position of thespring ends 31, 38 with knife bearing 48, 49.

As already mentioned, the construction shown is merely a typicalembodiment of the invention which does not restrict the latter; on thecontrary, many other embodiments and applications are possible. Thus,any torsion of the spring can also be counteracted byusing instead ofthe steel band, two parallel'wires or an extended connecting end of thespring or a reduced number of turns of the spring, or by using springswound in right-hand and left-hand directions. Then again, the tensionspring, instead of being of steel, may be made of some other workingmaterial, as for instance rubber. Moreover, instead of having mechanicalindication by a pointer, the balance may have optical indication bymeans of an illuminated image.

It will be understood that modifications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention, but it is understood that this application is to be limitedonly by the scope of the' appended claims.

' The invention is hereby claimed as follows:

1. A measuring instrument for measuring a mass through the measurementof a force comprising, a horizontally arranged main lever pivotallysupported adjacent one end by aknife bearing, a set of rods including avertical rod pivoted at one end thereof at the other end of the mainlever and at the other end thereof to a restraining link, an indicationsystem corresponding to said set of rods, means for applying the load tobe measured to the main lever between the knife bearing and the rod end,a vertically extending resilient member counteracting the load, andadjustablemeans mounting the resilient member between a fixed supportand the main lever so that the operation of the resilient member isalways linear. x

2. A measuring instrument as defined in claim 1, wherein said loadapplying means includes a knife bearing connection.

3. A measuring instrument as defined in claim 2, wherein said resilientmember is a coil spring.

4. A measuring instrument as defined in claim3, wherein said adjustablemounting means includes means at the fixed support for shiftinglaterally the respective end of the springand means on the main leverfor shifting laterally the respective end of the spring.

5. A measuring instrument as defined in claim 4, wherein said means atthe fixed support includes a pair of spaced supports slidably mounting across bar to which one end of the spring is attached, and set screwmeans on the support for locking the bar in place.

6. A measuring instrument as defined in claim 5, wherein said means atthemovable support includes a bell crank adjustably secured to the mainlever, and a knife bearing connection between the bell crank and thespring.

7. A measuring instrument as defined in claim 6, wherein said bell crankincludes a short arm extending vertically and a long arm extendinghorizontally, a horizontal row of holes in the end of the short arm, a

horizontal row of holes in the main lever, a swivel pin engaging in ahole of the main lever aligned with a hole of the bell crank, a tongueon the end of the long arm,

and a pair of opposed regulating screws on the main lever between whichthe tongue is received to adjust the bell crank about the swivel pin.

8. A measuring instrument as defined in claim 7, wherein the spacingbetween the holes in each row is equal while the spacing of the holes inthe main lever is different from that of the bell crank.

9. A measuring instrument as defined in claim 8, wherein the spacing ofthe holes in the bell crank is one and one-half that of the spacing ofthe holes in the main lever. I

10. A measuring instrument as defined in claim 9, and means for lockingthe bell crank and main lever together following an adjustment.

11. A measuring instrument as defined in claim 10, and means between themovable end of the spring and the knife bearing connection to the resisttorsion of the spring.

12. A measuring instrument as defined in claim 11, wherein said torsionresisting means is in the form of a steel band.

1. A measuring instrument for measuring a mass through the measurement of a force comprising, a horizontally arranged main lever pivotally supported adjacent one end by a knife bearing, a set of rods including a vertical rod pivoted at one end thereof at the other end of the main lever and at the other end thereof to a restraining link, an indication system corresponding to said set of rods, means for applying the load to be measured to the main lever between the knife bearing and the rod end, a vertically extending resilient member counteracting the load, and adjustable means mounting the resilient member between a fixed support and the main lever so that the operation of the resilient member is always linear.
 2. A measuring instrument as defined in claim 1, wherein said load applying means includes a knife bearing connection.
 3. A measuring instrument as defined in claim 2, wherein said resilient member is a coil spring.
 4. A measuring instrument as defined in claim 3, wherein said adjustable mounting means includes means at the fixed support for shifting laterally the respective end of the spring and means on the main lever for shifting laterally the respective end of the spring.
 5. A measuring instrument as defined in claim 4, wHerein said means at the fixed support includes a pair of spaced supports slidably mounting a cross bar to which one end of the spring is attached, and set screw means on the supports for locking the bar in place.
 6. A measuring instrument as defined in claim 5, wherein said means at the movable support includes a bell crank adjustably secured to the main lever, and a knife bearing connection between the bell crank and the spring.
 7. A measuring instrument as defined in claim 6, wherein said bell crank includes a short arm extending vertically and a long arm extending horizontally, a horizontal row of holes in the end of the short arm, a horizontal row of holes in the main lever, a swivel pin engaging in a hole of the main lever aligned with a hole of the bell crank, a tongue on the end of the long arm, and a pair of opposed regulating screws on the main lever between which the tongue is received to adjust the bell crank about the swivel pin.
 8. A measuring instrument as defined in claim 7, wherein the spacing between the holes in each row is equal while the spacing of the holes in the main lever is different from that of the bell crank.
 9. A measuring instrument as defined in claim 8, wherein the spacing of the holes in the bell crank is one and one-half that of the spacing of the holes in the main lever.
 10. A measuring instrument as defined in claim 9, and means for locking the bell crank and main lever together following an adjustment.
 11. A measuring instrument as defined in claim 10, and means between the movable end of the spring and the knife bearing connection to the resist torsion of the spring.
 12. A measuring instrument as defined in claim 11, wherein said torsion resisting means is in the form of a steel band. 